1. Field of the Invention
The invention relates to an auxiliary stage for preparing an electron microscope specimen and a method of utilizing the auxiliary stage.
2. Description of the Prior Art
In the semiconductor fabricating process, some small particles and defects are unavoidable. As the size of devices shrinks and the integration of circuits increases gradually, those small particles or defects affect the properties of the integrated circuits more seriously. In order to improve the reliability of semiconductor devices, a plurality of tests and monitors is performed continuously to find the root cause of the defects or particles. Then, process parameters can be tuned correspondingly to reduce a presence of defects or particles so as to improve the yield and reliability of the semiconductor fabricating process.
The scanning transmission electron microscope (STEM) is a combination of transmission electron microscope (TEM) and scanning electron microscope (SEM) in one instrument, which is a very important instrument used in material analysis.
Generally speaking, the optimum thickness of an STEM specimen needs to be smaller than 0.1 μm. Therefore, the specimen needs to be thinned by a focus ion beam (FIB) tool for reaching the optimum thickness. Before using the focus ion beam, a layer of platinum is coated on the specimen by a platinum sputter to increase the specimen conductivity and the surface resolution. However, since the traditional platinum sputter uses clay as a specimen stage, the solvent in the clay will pollute the chamber of the platinum sputter during the sputtering.
Moreover, when the STEM specimen is bombarded by electrons for a period of time, carbon may accumulate on the surface of the specimen, and the resolution will decrease. Therefore, a plasma cleaner is used to clean carbon accumulated on the specimen. However, the current plasma cleaner is only designed for TEM specimens. A STEM specimen can not fixed in the chamber of the plasma cleaner properly.
Therefore, a novel stage is needed to hold the STEM specimen during the specimen preparation process such as platinum sputtering, removing amorphous silicon or removing carbon.